According to the American Cancer Society website, Non-Hodgkin lymphoma (also known as non-Hodgkin’s lymphoma, Non-Hodgkin’s disease, NHL, or sometimes just lymphoma) is a cancer that starts in the cells of the lymph system, which is part of the body’s immune system.1 It is a type of cancer of the blood that affects the white blood cells, which are usually involved in protecting against infections. NHL is not a single disease, but rather a group of at least 31 closely related cancers that affect the lymphatic system.2 Although the different types of NHL have some things in common, particularly their lymphatic origin, they differ in their appearance under the microscope, their molecular features, their growth patterns and their impact on the body.2 Pertinent Anatomy and Lymphatics
Figure 1: The Lymphatic System
Adapted image from http://lymphoma-faq.org/images/lymphatic_system.jpg The lymphatic system (Figure 1), the target of lymphomas, includes the lymph nodes and other organs that make up the immune and blood-forming (hematopoietic) elements of the body. The lymph nodes are oval, pea-sized organs. They are found beneath the skin along the route of the large blood vessels, and they are grouped in areas such as the neck, underarms, groin, abdomen and pelvis. The lymph nodes are linked throughout the body by narrow tubes known as the lymphatic vessels. The vessels carry lymph from the body’s tissues; chyle, the fluid from the intestines during digestion; lymphocytes, the specialized white blood cells; and other blood cells. The lymphatic fluids and lymphocytes ultimately are funneled back into the bloodstream through a connection in the left upper chest. Other organs that contain lymphatic tissue and are also affected by lymphomas include the spleen, thymus gland, bone marrow, and the tonsils. Non-Hodgkin’s lymphomas begin in the lymphatic tissues, the white blood cells known as lymphocytes, and can invade other organs. Abnormal lymphocytes, which grow and multiply uncontrollably, often collect in lymph nodes, which as a result become swollen. These abnormal lymphocytes become lymphomas.2 Pathology and Histology
In 2006 the estimated number of new NHL cases in the United States was 59,000; deaths from NHL were 19,000.3 NHL is primarily a disease of older populations, with a median age at diagnosis of 65 years. There has been an increase of NHL incident rates during the last four decades, with a doubling between 1970 and 1990.3 The increase in incidence of NHL has been partly attributed to advances in molecular diagnostic techniques, the aging of the population, the acquired immune deficiency syndrome (AIDS) epidemic, other infectious agents, and occupational exposures. 3
Researchers have discovered that lymphomas are genetic alterations of the B and T lymphocyte cells. The exact causes of NHL, are largely unknown.4 Researchers have identified many risk factors such as exposure to particular infectious agents and reduced immune function. Burkitt’s lymphoma is caused by the Epstein-Barr virus. Serologic (blood) studies have shown an association between human T-cell leukemia/lymphoma virus (HTLV-1) and T-cell leukemia/lymphoma.4 AIDS patients have a 165% increased risk of developing NHL in the first 3.5 years after their AIDS diagnosis. Other certain infections that lead to a higher risk include Helicobacter pylori, and Hepatitis C virus. Having certain types of infections increases your risk of developing lymphomas, yet, lymphoma is not contagious, and you can’t catch lymphoma from other people.5 Heart and kidney transplant patients are also at and increased risk due to them being immunosuppressed.4 People exposed to ionizing radiation are at a greater risk of developing lymphomas. Atomic bomb survivors, who were exposed to 100 centigray (cGy) or more, are at an increased risk for lymphomas. Patients receiving radiation...